Dragon's Lair Fans - Arcade Lifestyle

General Chat => Technical Area => Topic started by: ckong on September 18, 2014, 07:59:05 PM

Title: Repair of a broken MTC900 chassis
Post by: ckong on September 18, 2014, 07:59:05 PM
A loooooong time ago, in my early days of arcade collecting, in fact during my (dark) Mame years, I bought a generic cab with a not so good monitor in it. I also bought a tested and working tube with a MTC 900 chassis at the same day.

In those days I thought that electricity is electricity and I had never hear the word 'isolation transformer'. A few days after the purchase of the generic cab I decided to swap the monitor. I made the swap, noticed the little sticker mentioning that the monitor works on either 128V or 220V (yes, you may laugh now), knew that my wall socket produces 220V, connected the monitor to the wall socket and ...... it was dark in house!!!  :o :o :o  I of course knew right away that something was wrong. Not knowing what (at that time) I just stored the monitor in the attic where it has been for 6 years or so.

But next week I want to test some Hantarex chassis that I got from Blanbek and I want to give the 'old one' another try also.

However, I guess I first need to repair that one. What gets normally broken after a stupid action like I did?  I already checked the 3 fuses on the power board of the 900 chassis but they are OK.
Title: Re: Repair of a broken MTC900 chassis
Post by: Etienne MacGyver on September 18, 2014, 08:35:17 PM
My knowledge of that does not reach that level, but i have heard that operating without an isolation transformer can serious f#ck up the chassis...
Title: Re: Repair of a broken MTC900 chassis
Post by: italiandoh on September 18, 2014, 08:43:10 PM
The MTC900 does not work on either AC voltages you mentioned, but requires BOTH. 128 V AC is for the normal operation, 220 V AC is for the degauss circuitry. You need a 220 V -> 128 V AC stepdown transformer to operate it. If you plugged 220 V AC into the 128 V AC input you more than likely fried something into the power supply section of the chassis.

Matteo
Title: Re: Repair of a broken MTC900 chassis
Post by: ckong on September 18, 2014, 09:15:27 PM
The MTC900 does not work on either AC voltages you mentioned, but requires BOTH. 128 V AC is for the normal operation, 220 V AC is for the degauss circuitry. You need a 220 V -> 128 V AC stepdown transformer to operate it.

Yes,  I know that for quite some time now,  but not 6 years ago  ;D.
Title: Re: Repair of a broken MTC900 chassis
Post by: ckong on September 18, 2014, 09:38:06 PM
Double post
Title: Re: Repair of a broken MTC900 chassis
Post by: Etienne MacGyver on September 18, 2014, 09:59:50 PM
Did you hookup the 220 part to the 220 in on the monitor connector?

If yes, then maybe only the degauss circuit my have damage as the 220 is only used for the degauss and you 128 "monitor part" is unharmed..

If you connected the 220 to the 128 volt input, then i think the chassis has serious damage.

I would say, try it in a zacc, that has the right connectors and transformers.
I would disconnect the game pdb though  ;)
Title: Re: Repair of a broken MTC900 chassis
Post by: ckong on September 18, 2014, 10:20:40 PM
Did you hookup the 220 part to the 220 in on the monitor connector?

If yes, then maybe only the degauss circuit my have damage as the 220 is only used for the degauss and you 128 "monitor part" is unharmed..

If you connected the 220 to the 128 volt input, then i think the chassis has serious damage.

I would say, try it in a zacc, that has the right connectors and transformers.
I would disconnect the game pdb though  ;)

Yep,  I did 220 to 220 and yes,  will do  :)
Title: Re: Repair of a broken MTC900 chassis
Post by: vernimark on September 19, 2014, 12:15:29 AM
As italiandoh mentioned i think you damaged the power section only... if you are lucky...
If you have another chassis compare component of that part

Title: Re: Repair of a broken MTC900 chassis
Post by: ckong on September 19, 2014, 08:14:05 AM
As italiandoh mentioned i think you damaged the power section only... if you are lucky...
If you have another chassis compare component of that part



I have blanbeks chassis to compare,  will do that when my vanguard is returned from Hilversum,  as Etienne said,  it is much easier to test all chassis with a Zacc cab on hand.
Title: Re: Repair of a broken MTC900 chassis
Post by: Etienne MacGyver on September 19, 2014, 08:34:47 AM
You should have mentioned it before, i have a spare zacc powerbrick i could bring to EC14...

too late for that now  :D

EDIT:

Looking at the schematics of the MTC900, it looks like the degauss circuit is isolated from the other circuit. (wich makes sence ofcourse  :D )

so i think if you blow something, its only in the degauss circuit and the other part is unharmed.

Title: Re: Repair of a broken MTC900 chassis
Post by: vernimark on September 19, 2014, 01:43:17 PM
Last month I tried to repair a MTC900 chassis but every time I plugged it (in the right way) the security switch powered off.
I thought the problem was related to the ground or something similar but checking the degauss circuit I discovered the board had been hacked in order to work with 128VAC only.
Please check any hack, as a fuse removed or disconnected and 2 tracks after the power connector short circuited.

Just an idea...

Title: Re: Repair of a broken MTC900 chassis
Post by: level42 on September 19, 2014, 05:24:51 PM
You could also ask Grantspain on the BYOAC forum. He's a real Hantarex expert.
Title: Re: Repair of a broken MTC900 chassis
Post by: nilfisk on September 21, 2014, 12:57:16 PM
About 10+ years ago, when I was in my early days too and knew nothing about monitors, too, I once accidentally swapped the 220 vac input with the 110 one on a MTC9000 chassis. Big bang, room fuse went off.

I checked my wiring, discovered the fault, swapped out the cables and put on power again .... and the monitor is working to this day :)

So not always will something like a swapped power line kill the monitor - but I agree that I was very fortunate, and this is probably a rare example.
Title: Re: Repair of a broken MTC900 chassis
Post by: ckong on September 22, 2014, 01:07:20 PM
not really topic related, but ...

I have a MTC 900E (europe version) with a NE04 neckboard. I read somewhere that a Videocolor A51-420X tube fits, but does a Videocolor A51-421X fits also (the pins on the neckboard matches with the connector on the neck, but I don't dare to power the monitor on yet)?

If not, then I will have to swap the tube for a 231X
Title: Re: Repair of a broken MTC900 chassis
Post by: Etienne MacGyver on September 22, 2014, 02:47:18 PM
maybe this helps :

http://tubular.atomized.org/

compare the tubes and connections, and maybe they are compatible
Title: Re: Repair of a broken MTC900 chassis
Post by: level42 on September 22, 2014, 04:09:22 PM
AFAIR the 900E is actually (and strangely) the one that was aimed at the US, not Europe.

About the question: you can also use this document:

http://www.andysarcade.de/data/electronics/testing/mueter/mueter_crt_liste_2009.pdf
Find the tubes, and if they both need the same adapter than it should be pretty safe to try it.


HOWEVER.......you are probably swapping tubes with the yokes still on them and you will also have to measure the resistance of both the H and V coils of the yoke. They need to be at least a bit close....

Title: Re: Repair of a broken MTC900 chassis
Post by: level42 on September 22, 2014, 04:13:09 PM
Yep just checked and both those tubes need the same adapter (815) and thus you. An swap them neck-wise....

The yoke issue has still to be investigated by yourself :)
Title: Re: Repair of a broken MTC900 chassis
Post by: ckong on September 22, 2014, 04:39:55 PM
AFAIR the 900E is actually (and strangely) the one that was aimed at the US, not Europe

Not quite,  the 900E came in 2 versions,  an US version and an European version. I have the European version and made today 2 working monitors with them,  with the help of 2 A50-231x tubes.   :)
Title: Re: Repair of a broken MTC900 chassis
Post by: PaulSwan on October 07, 2014, 05:51:18 AM
The 220V degauss usually doesn't care if it's isolated or not - in some games it's tapped off the line side un-isolated. The 128VAC always needs to be isolated.

AFAIK all 900 & 900E necks & yolks are generally compatible in the common S4/NE04 varieties. There are some oddball rarer ones that are not. However, there are some minor variations in the chassis componentization per tube that might cause trouble.

See http://www.zzzaccaria.com/MrDoRestoration.htm (http://www.zzzaccaria.com/MrDoRestoration.htm) for one possible example of mismatching chassis with tube.

http://www.zzzaccaria.com/images/Projects/SuperCobraRestoration/SAM_4647w.JPG (http://www.zzzaccaria.com/images/Projects/SuperCobraRestoration/SAM_4647w.JPG) is the Hantarex doc for chassis-tube variations.

Paul.



Title: Re: Repair of a broken MTC900 chassis
Post by: level42 on October 08, 2014, 11:51:42 AM
I think my first comment about the 900E is not entirely correct.
There is a 900E and a 900E USA.

At least, there are different service manuals for both types. I know this since I picked up a 900E last weekend and it came with the manual.

The manual didn't look familar to me so I searched on the internet and found both manuals for a 900E (the one I got) and a 900E USA.

 The mainboard number differs, one is DE2 the other DE4 but I don't know which is on which from the top of my head. Interesting fact about the one I picked up: the previouse owner put a mains cord on it with a regular plug and I saw it working at his house so without isolation transformer and on 230VAC.

As a sidenote, he also hacked on a SCART connector....